1. Field of the Invention
The present invention relates to an image forming apparatus and an image forming system for encrypting image data read from a document.
2. Description of the Related Art
In recent years, information technology (IT) has progressed in business organizations, governments, municipal institutes, or like institutes. Information sharing, reduction of administration fees, and a like advantage have been provided by computerizing paper documents. In the technical field of image forming apparatuses such as copiers, digitization has also progressed. There have been known image forming apparatuses, in which document images are acquired as electronic data, and image data read from documents is stored in an HDD (hard disk drive) or a storage medium such as a detachable memory card. Further, complex machines having functions as a scanner, a printer, a facsimile machine, or a like device, in addition to the function of a copier, have been widespread, and document computerization with use of the complex machines has been encouraged.
As the document computerization has progressed, it is highly likely that the computerized information may be carried out of the institutes such as offices administering the documents. This may increase likelihood that classified information may be leaked. In view of this, there are proposed image forming apparatuses constructed such that: access to computerized classified document data is restricted by a password; computerized classified document data is encrypted; or a predetermined password entry is required in forming an image of an encrypted classified document, and image output is authorized exclusively when a right password is entered (e.g. see Japanese Unexamined Patent Publication No. 2005-295541).
In the image forming apparatus requiring the password entry in forming an image of a classified document, or in the image forming apparatus constructed such that classified document data is encrypted for storage, the following drawbacks may be involved. For instance, in the case where a password is known to a third party when a user enters the password to the image forming apparatus, or an encryption key is leaked, the classified document may be read, and a storage medium storing the image data of the classified document may be carried outside the institute administering the classified document, or the HDD storing the image data of the classified document may be carried outside the institute by maintenance or a like service. In such a condition, it is possible for an unauthorized person to acquire the classified document data, using the password known to the third party or the encryption key, from the storage device such as the HDD or the storage medium which has been carried outside the institute. This may cause leak of the classified information.